Took a look at SymphonyOS again and booted up their live CD. Doesn’t do too much off the live CD at least. I’m not finding it terribly radical. The corner zones are new implementation wise. Things like the RSS/Weather feeds are basically gdesklets. You could also hack nautilus to hold html snippets. Regular apps are still be used (gaim, firefox). The menus are layed out on the screen but that shouldn’t be too hard to hack up. In short, GNOME pretty much has all the infrastructure to do this if we wanted to.
The little one is pulling herself up now, next stop is walking.